The objective of the proposed research is to understand the on-line operation of intermediate cerebellar networks during the motor control and learning of protective eyelid movements. This will be studied using the model of classically conditioned eyeblinks. A series of studies will be performed in rabbits to characterize the function of the inferior olive in movement control and in the acquisition of anticipatory protective reflexes. The proposed research is based on the general hypothesis that the cerebellum, together with extra-cerebellar circuits, is responsible for recognizing a threatening environmental situation and generating adaptive anticipatory behavior. The unique feature of these proposed experiments is their use of an innovative method for manipulating specific synaptic inputs to central neurons without affecting spontaneous tonic activity of investigated neural networks. The first experiments will examine the specific role of sensory signals, carried from the inferior olive to the cerebellum, in the expression and retention of learned movements. In the second series of experiments, the role of the cerebellar inferior olivary input in conditioned response acquisition will be examined. This latter research represents a fundamental test of the popular cerebellar learning hypothesis. The results of this research are important for understanding the mechanisms related to the acquisition and retention of anticipatory defensive behaviors, and also for improving the rehabilitation of patients with deficits in sensorimotor integration through the understanding of the mechanisms underlying motor learning and recovery of motor function.